Composite insole structure

ABSTRACT

Provided is a composite insole structure including: an insole body being oblong, having a front segment, a middle segment and a rear segment, being made of foam by foaming, and having hardness of 50˜80 OO; and a heel element made of plastic and disposed at the rear segment of the insole body. The middle area of the heel element is of greater thickness than the peripheral area of the heel element; hence, the middle area of the heel element is arched to be centrally raised and thus thinned toward the edge of the middle area radially. The heel element is of hardness of 35˜75 OO.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure relates to insoles and, more particularly, to a composite insole structure comprising non-foam elastomer.

2. Description of the Related Art

Conventional soles of sneakers and leisure shoes are mostly made of EVA foam or EVA mixed foam, and then rubber sheets are adhered to the undersides of the shoes. However, the heel portions of the soles sag under the weight of the shoe wearers and thus deform permanently. The soles made of EVA foam or EVA mixed foam are unable to resist compression and resultant permanent deformation, especially the heel portions of the soles. As a result, the sunken heel portions of the soles cause discomfort to shoes wearers or even render the shoes unfit.

An insole is mounted inside the shoe in an attempt to overcome the aforesaid drawback of the prior art. However, commercially-available insoles are also made of EVA foam, EVA mixed foam, PU or latex and are not specially designed to address the aforesaid drawback of the prior art. The insole thus made provides the same support force to the ball, arch and heel of the human foot. As a result, the commercially-available insoles are unable to effectively overcome the aforesaid drawback of the prior art.

BRIEF SUMMARY OF THE INVENTION

It is an objective of the present disclosure to provide a composite insole structure having structural features and providing support forces to different parts of the human foot, respectively, thereby preventing the heel portion of the sole of the shoe from being deformed and sunken.

In order to achieve the above and other objectives, the present disclosure provides a composite insole structure, comprising: an insole body being oblong and having a front segment corresponding in position to a human foot's ball, a rear segment corresponding in position to the human foot's heel, and a middle segment connecting the front segment and the rear segment, wherein the insole body is made of a foam by foaming and has an upper surface facing upward and a lower surface facing downward, with a superficial layer disposed on the upper surface of the insole body and adapted to come into contact with the human foot's sole; and a heel element made of a plastic and corresponding in shape to the rear segment of the insole body, wherein a middle area of the heel element is of greater thickness than a peripheral area of the heel element, wherein the middle area of the heel element is not only arched to be centrally raised but also thinned toward the edge of the middle area radially, wherein the heel element is disposed at the rear segment of the lower surface of the insole body.

The composite insole structure of the present disclosure uses different levels of material hardness to provide different support forces at different positions of the human foot's ball, thereby overcoming the aforesaid drawback of the prior art.

Preferably, the insole body is made of foam, such as EVA, PU, latex or gel form (thermoplastic rubber cross-linking foam), by foaming, and the range of optimal hardness of the insole body is 50˜80 OO.

Preferably, the heel element is made of PU gel, styrene block copolymer or natural rubber and has hardness of 35˜75 OO. Furthermore, the heel element is non-foam elastomer and is able to resist compression and resultant permanent deformation, thereby being able to bear the weight of a human being without ending up in deformation.

Preferably, the thickness of the thickest portion of the heel element is one to three times greater than the thickness of the rear segment of the insole body.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of the present disclosure.

FIG. 2 is an exploded view of the present disclosure.

FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 1 .

FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 1 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Directional expressions used herein, including the description of embodiments and claims, must be interpreted in accordance with the accompanying drawings. Identical reference numerals used in the embodiments and the accompanying drawings denote identical or similar components or structural features thereof.

Referring to FIG. 1 through FIG. 4 , a composite insole structure of the present disclosure comprises an insole body 10 and a heel element 30.

The insole body 10 is oblong and has a front segment 11 corresponding in position to the ball of the human foot, a rear segment 12 corresponding in position to the heel of the human foot, and a middle segment 13 connecting the front segment 11 and the rear segment 12. The insole body 10 is manufactured by performing a foaming process on a foaming material, such as EVA, PU, latex or gel form (thermoplastic rubber cross-linking foam or rubber foam. The hardness of the insole body 10 complies with ASTM D2204-5 specified by the United States. Regarding its grading standard, Shore Durometer Hardness is of 12 grades, depending on usage needs. The hardness of the insole body of the present disclosure is preferably 50˜80 OO in accordance with the grading standard in order to be comfortable.

The insole body 10 has an upper surface 14 facing upward and a lower surface 15 facing downward. The edge of the upper surface 14 of the insole body 10 has a flange 16 which extends upward. Starting from the front segment 11, the flange 16 protrudes from the upper surface 14 of the insole body 10 and extends toward the rear segment 12. The length of the extension of the flange 16 located at the middle segment 13 and corresponding in position to the arch is greater than the length of the extension of the flange 16 located at the other positions, such that the arch portion of the insole body 10 fits the human foot well.

A superficial layer 20 is disposed on the upper surface 11 of the insole body 10 and adapted to be in contact with the sole of the human foot. The superficial layer 20 is made of polyester, nylon, cotton or hemp and is in the form of woven fabric or non-woven fabric to enable the human foot to feel comfortable. A join surface 17 is disposed at the rear segment 12 of the insole body 10 and corresponds in position to the lower surface 15 of the insole body 10. A height difference is defined between the join surface 17 and the middle segment 13. The superficial layer 20 is attached to the upper surface 11 of the insole body 10 by adhesion or high frequency welding.

The heel element 30 is made of a plastic, such as PU gel, styrene block copolymer or natural rubber and is able to resist compression and resultant permanent deformation, thereby being able to bear the weight of a human being without ending up in deformation. The hardness of the heel element 30 is 35-75 OO in accordance with the grading standard of ASTM D2204-5. The heel element 30 corresponds in shape to the rear segment 12 of the insole body 10. The heel element 30 is thicker at the middle area than at the peripheral area; hence, the middle area of the heel element 30 is arched to be centrally raised and thus thinned toward the edge of the middle area radially. The edge of the heel element 30 has an arcuate lead angle 31 to not only connect to the edge of the rear segment 12 of the insole body 10 but also enable the insole to fit to the inside of the shoe when placed therein. The thickness of the thickest portion of the heel element 30 is one to three times greater than the thickness of the rear segment 12 of the insole body 10. For instance, if the thickness of the rear segment 12 of the insole body 10 is 4 mm, the thickness of the thickest portion of the heel element will be 4-12 mm. Therefore, the support provided by the composite insole structure is satisfactory. If the heel element 30 is overly thin, the support will be weak. If the heel element 30 is overly thick, not only will the heel portion of the sole be raised upward to cause discomfort to a shoe wearer, but the insole will also take up so much space in the shoe that the shoe will be rendered unfit. The heel element 30 is disposed at the join surface 17 of the rear segment 12 of the insole body 10. Thus, the height difference defined between the front edge of the heel element 30 and the lower surface 15 of the insole body 10 and corresponding in position to the middle segment 13 of the insole body 10 can be eliminated. The heel element 30 and the insole body 10 are coupled together by adhesion, secondary injection, or hot pressing.

It is important for different portions of the sole of the shoe to provide appropriate levels of strength of support forces to the human foot's sole, respectively. For instance, the insole body and heel element must provide their respective appropriate levels of strength of support forces to the human foot. To this end, the length of the heel element 30 is less than or equal to a half of the length of the insole body 10 or preferably ranges from a half to a quarter of the length of the insole body 10. Most preferably, regarding its length, the heel element 30 extends from the rear end of the insole body 10 in the direction of the front segment 11 to the middle of the middle segment 13.

The composite insole structure of the present disclosure is advantageous in that a user can directly put the composite insole structure inside the shoe. Furthermore, the insole body and heel element of the composite insole structure have different levels of hardness and are made of different materials. Moreover, the heel element is raised in order to compensate for the shoe sole's depression deformation which might otherwise cause discomfort to the human foot. In particular, the heel element is made of a plastic and thus is able to resist compression and resultant permanent deformation, thereby being able to bear the weight of a human being without ending up in deformation.

In addition, the composite insole structure of the present disclosure is effective in spreading a load and thereby precluding the shoe sole's depression deformation otherwise arising from lengthy compression typical of conventional shoe soles made of EVA. Therefore, the composite insole structure of the present disclosure renders shoe soles comfortable, reduces a waste of resources, and reduces carbon emissions to thereby contribute to environmental sustainability. 

What is claimed is:
 1. A composite insole structure, comprising: an insole body being oblong and having a front segment corresponding in position to a human foot's ball, a rear segment corresponding in position to the human foot's heel, and a middle segment connecting the front segment and the rear segment, wherein the insole body is made of a foam by foaming and has an upper surface facing upward and a lower surface facing downward, with a superficial layer disposed on the upper surface of the insole body and adapted to come into contact with the human foot's sole, and a heel element made of a plastic and corresponding in shape to the rear segment of the insole body, wherein a middle area of the heel element is of greater thickness than a peripheral area of the heel element, wherein the middle area of the heel element is arched to be centrally raised and thus thinned toward the edge of the middle area radially, wherein the heel element is disposed at the rear segment of the lower surface of the insole body.
 2. The composite insole structure of claim 1, wherein the heel element is made of PU gel, styrene block copolymer or natural rubber.
 3. The composite insole structure of claim 2, wherein the heel element is of hardness of 35˜75 OO.
 4. The composite insole structure of claim 3, wherein the insole body is made of a foam, such as EVA, PU, latex or gel form (thermoplastic rubber cross-linking foam), by foaming.
 5. The composite insole structure of claim 4, wherein the insole body is of hardness of 50˜80 OO.
 6. The composite insole structure of claim 1, wherein the heel element is made of PU gel, styrene block copolymer or natural rubber and is of hardness of 35˜75 OO.
 7. The composite insole structure of claim 6, wherein the thickness of the thickest portion of the heel element is one to three times greater than the thickness of the rear segment of the insole body, and the superficial layer is made of polyester, nylon, cotton or hemp.
 8. The composite insole structure of claim 5, wherein the edge of the heel element has an arcuate lead angle to connect to the edge of the rear segment of the insole body.
 9. The composite insole structure of claim 8, wherein a join surface is disposed at the rear segment of the insole body and corresponds in position to the lower surface of the insole body, wherein a height difference is defined between the join surface and the middle segment, wherein a height difference defined between the front edge of the heel element and the lower surface of the insole body and corresponding in position to the middle segment of the insole body can be eliminated.
 10. The composite insole structure of claim 9, wherein an edge of the upper surface of the insole body has a flange which extends upward, wherein, starting from the front segment, the flange protrudes from the upper surface of the insole body and extends toward the rear segment, wherein the length of an extension of the flange located at the middle segment and corresponding in position to the arch is greater than the length of an extension of the flange located at the other positions. 